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Hey folks, just got off my night shift and saw this post. I've had similar issues with my vinyl pool here in the PNW! When my CYA was through the roof last season (like 120+ ppm), my LaMotte CH test definitely gave me some weird purple-ish readings instead of the usual blue endpoint. I think the high stabilizer messes with the indicator dye somehow. My advice: get your CYA down first with partial drains/refills, then retest CH. Also, make sure you're using fresh reagents - old ones can give false colors too.

Hello everyone. As a yoga instructor, I approach pool chemistry with patience and observation. **First, breathe** - this is solvable! While high CYA can interfere with some tests, the LaMotte CH test (assuming it's the ColorQ or similar drop test) should be relatively resistant to CYA interference according to their documentation. Have you considered: - Testing your tap water's CH as a control? - Making sure you're adding exactly 10 drops of reagent R-0010L and swirling properly? - Checking if your sample tube is clean and free of residue? Sometimes our perception of color changes in different lighting too. Try testing in natural daylight if possible.

Just finished my morning run and saw this! **High CYA absolutely can cause color issues** - I've experienced it myself during marathon training season when I neglected my pool. Last summer, with CYA at 150 ppm, my CH tests were consistently purple instead of blue. The chemistry is that excess cyanuric acid can bind with calcium ions or interfere with the indicator. **Action plan:** 1. Test CYA immediately - if it's over 100 ppm, you need to dilute 2. For an accurate CH reading now, try diluting your pool sample 1:1 with distilled water, test, then double the result 3. Long-term: manage CYA better - use less stabilized chlorine! Stay persistent like training for a race - you'll get clear water and clear test results!

Cathy's dilution trick is solid! I've used that when I couldn't drain right away. Mila's point about lighting is key too - I've misread tests under my garage's yellow LED lights after night shifts. Try testing near a window. Also, what's your actual CH reading? If it's super high (like 500+), the color can shift toward purple anyway. And are you using the right comparator? The LaMotte CH test should go from pink→purple→blue, but if it's stuck at purple, something's off. PNW vinyl pool crew unite! Our rainy weather makes CYA management a nightmare since we don't get much splash-out dilution.

Jack makes excellent points about high CH levels potentially causing purple hues. Let's approach this systematically: **Possible causes of purple reading:** 1. **Very high CH** (>400 ppm) - test diluted sample as Cathy suggested 2. **Old or contaminated reagents** - check expiration dates 3. **Interference from metals** - copper or iron can tint the solution 4. **High CYA** - though less common with this specific test Could you share: - How old are your reagents? - Have you added any metal-based algaecides recently? - What's your pool's current temperature? (Cold water can affect reaction times) Sometimes the solution is simply to retest with fresh supplies while being fully present in the testing process.